Made up of boys aged 14-19, Only Boys Aloud was set up in 2010 by Rhys-Evans, who is also behind the successful Only Men Aloud.

Video: The Arts Show interview with Tim Rhys-Evans

His 141-strong younger version has been signed by record giant Sony and will tour the country next year.

“There are lots of great Welsh choirs out there but we took the bull by the horns and entered Britain’s Got Talent and it has been the most incredible year,” said Rhys-Evans.

“It has been wonderful to see how the boys have just grown through the whole process.

“To see them chatting to Gary Barlow and Olly Murs at the X Factor final is amazing. “Without Only Boys Aloud it is doubtful that those sorts of meetings and opportunities would have happened for these lads.”

It is a far cry from his own experiences of huge inhibition as a teenager, whose love of music was like a guilty secret.

His passion for music began at an early age but as a child, he says, would have seen him bullied.

“I had piano lessons from five and quickly music became my life but I hid anything to do with choir because it prevented me from getting my head kicked in,” he said.

Spearheading the Only Boys Aloud project has represented a shift in culture, of which Rhys-Evans is most proud.

He wanted to inspire a new generation of boys to discover choral singing, and the project allowed boys from all over South Wales to come together to sing. Two years later, they’re known all over the UK.

“Suddenly being part of a choir is cool. In fact recently a lad came up to me and said ‘Can we get some hoodies made with the Only Boys Aloud logo on?’” he said.

“I asked why and he said ‘It’ll really help me pull’.

“It was that moment I knew there had been a huge shift – a real turnaround.”

The choir has released their debut album , which contains a mixture of traditional music such as the chart-topping Calon Lan and Gwahoddiad, as well as reinterpretations of songs like Coldplay’s Paradise and Take That’s Never Forget.

“The boys are having such a great time with the choir and now it’s cool to be part of it. I think it is changing the outlook of a generation, who are from communities that have previously failed to aspire to such great things,” he said.

“I am deeply passionate about Wales and the Valleys but it incenses me that so many of the things in life that are joyful and life affirming like singing are often shot down.

“I think a lot of it is about a lack of confidence. As a nation we often put ourselves down.

“The ethos of OBA was to engender a sense of aspiration.

“We have boys who are going to Cambridge to study veterinary surgery alongside building apprentices and in the choir they are all equal.

“It’s been a really cohesive thing and great for communities.”

Brought up in Tredegar, Rhys-Evans followed his dream and became choral director at the Royal Welsh College of Music and Drama.

That year he decided to do the same for boys. They finished third in Britain’s Got Talent in May 2012.

“When I was about 11 the guts were ripped out of my community and so many others when the mines were closed. I think everyone felt there was a lack of opportunity,” he said.

“The associated problems that go with that, drug and alcohol abuse, have been a factor for some of the boys. Some have ended up in care.

“That’s the whole reason this started. Choral singing is a stronghold of the Valleys and I wanted to use it as a way of getting teenage boys doing something positive.

“To see the buzz they get singing together is incredible. They know they don’t have to be victims of circumstance. They can achieve just as much as anyone else in life.

“I’m not saying the choir solves everything but it does give the younger generation a reason to believe in where you come from and what can be achieved.

“Hanging out with Simon Cowell isn’t something that happens for everyone.”

Among the highlights of the last four years have been performing at Buckingham Palace and working with Bonnie Tyler. The boys have also set up a charity.

But the choir’s biggest stage so far was Cowell’s enormously popular ITV talent show.

“Britain’s Got Talent is something I wouldn’t have even contemplated a year ago but we decided to enter last February and what that has done for us is to allow us to show what we do on a national and international platform,” he said.

“It was a gift of an opportunity to take Welsh culture and celebrate it, which we don’t do enough.

“The fact that Calon Lan was trending on Twitter was a pretty awesome achievement.

“It has been a privilege to be able to introduce that to Simon Cowell.

“But for me it’s just about a love affair with what we are doing. I struggle with the cut and thrust of the business side.

“I’m not a big fan of reality TV. We entered the men into Last Choir Standing and then the boys into BGT - so I have taken the opportunities.

“What I can’t stand is when you find someone who has done a bit of kareoke and they think that earns them a right to become the next big thing.

“It is about hard work and we drum that into the boys. That’s why we sang Calon Lan and not We will Rock You.”